I've started to use ID number for posts on some WordPress installs. I've noticed before that changing any information with categories ends up changing the ID number even of those. As a result, I've had categories go from just the hundreds to 5 digit numbers very quickly and I'm concerned about Post ID going the same route.
Each time I have a post revision, it uses a new ID number for Post ID. As a result, I'll have a post ID of 100 today and then potentially 500 tomorrow and then work it's way into the thousands. In addition to having to delete all these drafts and revisions, I'd like to prevent my post ID numbers from growing exponentially large. I can see this reaching the 6 digit level quickly and 7 digit posts not as impossible as I originally thought.